Electrical door interlock



May 26 194-2. L, BBQWN ELECTRICAL. DbOR INTERLOCK Filed June 29, 1940 I INVENT OR. L. BROWN ANDRE W Z ATTORNEY.

Patented May 26, 1942 ELECTRICAL DOOR. INTERLOCK Andrew L. Brown; Brooklyn, N. Y., assignor to Radio Corporation of America, a. corporation of Delaware Application June 29, 1940, Serial. No. 343,102

4 Claims.

This invention relates to a new and novel electrical door interlock and particularly deals with a means for interrupting. a power or control circuit.

An object of this invention is to provide a foolproof, quick make and break door interlock which will fulfill the several requirements of protection, t'emper-proofness, and simplicity, which has been a vexing problem to many engaged in the major problems of radio transmitters and equipment generally.

A feature of this invention is the action of the interlock upon the opening of a door. A movable member is caused to make either a quick break or a quick make of the series connection between two spring members located on a fixed member to which the external circuit is connected. Also, the line contact members are concealed, so that willful disabling of the interlock is prevented This invention will best be understood by referring to the accompanying drawing, in which:

Fig. 1 is a plan view of the interlock switch;

Fig. 2 is a sectional detail of the spring contact;

Fig. 3 is a plan view of the door in the open position.

Referring now in detail to the drawing, a fixed member which is preferably made of a phenolic insulating composition, consists of two half portions I and 2. A movable member 3, which is also made of insulating material, is split in a manner similar to that of members I and 2. The movable and fixed members are so shaped that when combined in the closed position, they form substantially a semi-circle. Members I and 2 are provided with an arcuate portion 4 which forms an enclosing channel for an arm 5 which is secured to movable member 3. On the right hand end of arcuate channel 4 and orthogonally to it, there are located two circular channels 6 and I which have a larger bore than that of channel 4, but are a different size from each other. For example, channel 6 is larger than channel I. Within channels 6 and I are located elastic insulating rings 8, preferably that of sponge rubber, and as shown in detail in Fig. 2, in which two helical ring-shaped spring elements 9 and III are located. A flexible connection II and I2 is soldered to contact springs 9 and I; Flexible leads II and I2 are located within a slotted channel portion I4 and I and terminate in holes I6 and I! located substantially near the center of the fixed member. I

Movable member 3 isprovided with a retaining channel I8 for supporting the arcuate plug. portion 5. On the extreme left hand portion of memberB is provided a square shaped washer I9 underneath which is located a spring member 20. The right hand end portion of member 5 is provided with a metal insert 2 I having a plurality of grooves 25 and 26, the diameter of which is substantially equal to but slightly larger than. that of the inner diameter of helical contact springs 9 and I8. The insulating and conducting surfaces aredisposed midway of the hump of the grooves so that the annular spring contacts will jump toggle fashion one way or the other'when the peak is reached. It will be noted that shortcircuiting plug member 5 is shaped such that its point of radius is at the same point as the door hinge member 23, so that upon opening of the door 24, member 5 falls within the channel 4 of fixed member I. The extreme tip of insert member 2| may be provided with a section of insulatlng material 21. The two split portions I and 2 are joined together by any suitable means, such as screws 28. The fixed and movable members are secured to the panel 29 and door 24 by means of a plurality of screws 30 which are threaded into metallic inserts 3|. Although flexible leads I I are shown soldered to spring member 9 in Fig. 2, the spaces I4 and I5 could otherwise be fitted with a suitable screw terminal, the object being to conceal the external point of connection so that a willful disabling of the interlock will be more difficult. The short-oircuiting member 5 is, so shaped at its extreme free end that a quick make and break action will result, due to the restricting of the helical spring rings 9 and ID. The compression spring 20 fastened to the secured end of the movable member functions in part to permit this action independent of the relative motion of the door 24 to frame 29, and also allows for a slight misalignment between the fixed and movable portions.

Although only one modification of this invention is shown, it is to be distinctly understood that it is capable of taking other shapes, and therefore should not be limited precisely thereto.

What is claimed is:

1. An interlock switch comprising a fixed contact having two ring-like split contact terminals located therein, one of said ring-like split contact terminals having a larger diameter than the other, a movable contact member, said fixed and movable members together forming substantially a semi-circular device, said fixed contact member being secured to the frame of a radio transmitter, said movable contact member se.

tact having two ring-like split contact terminals 7 located therein, one of said ring-like split contact terminals having a larger diameter than the other, a soft rubber member surrounding each of said ring-like spring contact terminals, a movable contact member, said fixed and movable members together forming substantially a semi-circular device, said fixed contact member being secured to the frame of a radio transmitter, said movable contact member secured to the door of a radio transmitter, a hinge fastened to said door and said frame, an arcuate rod-like arm secured to said insulating member, the central radius of said arcuate arm having its point of origin at the pivot point of said hinge, and means on the free end of said arcuate member to short circuit said spring-like contacts on the fixed member.

3. An interlock switch comprising a fixed contact member having an arcuate channel therein, said fixed contact member being formed of two split insulating members joined together, two ring-like split contact terminals located at right angles to the axis of said arcuate channel,

one of said ring-like split contact terminals having a larger diameter than the other, a soft rubber member surrounding each of said ring-like spring contact terminals, a movable contact member, said fixed and movable members together forming substantially a semi-circular device, said fixed contact member being secured to the frame of a radio transmitter, said movable contact member secured to the door of a radio transmitter, a hinge fastened to said door and said frame, an arcuate rod-like arm secured to said insulating member, the central radius of said arcuate arm having its point of origin at the pivot point of said hinge, and means on the free end of said arcuate member to short circuit said spring-like contacts on the fixed member.

4. An interlock switch comprising a fixed con tact having two split contact terminals located therein, a movable contact member, said fixed and movable members together forming substantially a semi-circular device, one of said split contact terminals having a larger diameter than the other, a soft rubber member surrounding each one of said split contact terminals, said fixed contact member being secured to the frame of a radio transmitter, a hinge fastened to said door and said frame, an arcuate rod-like arm secured to said insulating member, the central radius of said arcuate arm having its point of origin at the pivot point of said hinge, and means on the free end of said arcuate member to short circuit said spring-like contacts on the fixed member when said door is in the closed position.

ANDREW L. BROWN. 

